الفهرس 
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Abstract
”Odontogenic tumors are neoplastic lesions that originate from cells which involved in tooth formation. Most of OTs are benign, but with behaviors similar to malignant tumors as local recurrence and high invasiveness characters. Neoplastic lesions could originate from DCs. Also, AC overlaps the histopathological characters of benign AB that leads to misdiagnosis with direct implication on managing protocol. Hence, IHC analysis of these types of tumors may be useful. This study was conducted in order to evaluate the role of SOX2, GPC3 and Syn1 proteins in DC, AB and AC and to correlate between them with different clinicopathological parameters of these types of OTs. The present study was retrospectively carried out upon 54 cases, which were distributed as follow: 10 DC, 29 AB (19 Conventional AB and 10 UAB) and 15 AC archival paraffin embedded tissues, which were employed to prepare sections for H&E stain to confirm the diagnosis and for IHC stain with SOX2, GPC3 and Syn1 according to the manufacturer’s instructions. Then, they were evaluated for immune staining. The studied cases revealed a high tendency to occur in males. The posterior mandible was the most frequent site. All DC cases appeared radio-graphically as well defined uni-locullar radiolucency without cortical perforation. AB cases were mostly appeared as well defined multi-locular radiolucency and most of cases showed no cortical perforation. Most of AC cases appeared as ill-defined multi-locular radiolucency with cortical perforation. Conventional AB was more frequently observed than the Unicystic type. Moreover, as regard to the histopathological pattern of Conventional AB; the follicular pattern was the most commonly observed followed by the Plexiform pattern. SOX2 expression in all the studied DC cases was detected in the nuclei of the cyst lining epithelial cells without CT reaction. While, in AB it wasn’t expressed by most of the cases especially the UAB and was restricted to the nucleus of the outer basal cells with weak to absent in the central areas. Furthermore, most AC cases showed focal nuclear and cytoplasmic reaction near the tumor peripheries and areas that lost their normal cellular architecture. GPC3 reaction wasn’t found in most of DC cases, the expression was observed in the cytoplasm of the cyst lining epithelial cells without CT reaction. While, in AB it was expressed by most of the cases in the cytoplasm of the outer palisading cells with variable expression inside the tumor follicles, in addition to the CT close to the follicles only in the Conventional type. Moreover, all the studied AC cases exhibited diffuse GPC3 cytoplasmic and nuclear reaction in the tumor follicles and CT with predominantly weak staining in central areas. Syn1 expression was cytoplasmic/ membranous in all the studied groups. In DC, Syn1E was observed in all cases. But, Syn1S wasn’t found in the majority of cases. Moreover, in most of AB cases, Syn1E was detected in the Conventional type in basal and suprabasal cells. In UAB appeared in the neoplastic cystic epithelial cells, in the intraluminal projections, and in some tumor islands contained within the cyst wall. Moreover, Syn1S was observed in the connective tissue close to the epithelial neoplastic cells in both Conventional and the Unicystic type. Statistical analysis of SOX2, GPC3 and Syn1 expression among the studied cases, revealed no significant differences between these markers and the clinical data. But, there were significant differences between DC and UAB, Conventional AB and AC. There was direct positive correlation between Syn1S and GPC3 in AB and AC. Moreover there were direct positive correlations between SOX2, GPC3 and Syn1S in AC. No correlation was found between epithelial and stromal syndecan-1 in any of the studied groups. According to the three markers expressions, Desmoplastic AB subtype seems to behave in a more aggressive manner than other subtypes.